HOW FOAM EXTINGUISHES A FLAMMABLE LIQUID FIRE

Fire burns because there are four elements present. These elements are heat, fuel, air (oxygen) and a chemical chain reaction. Under normal circumstances if any one of the elements is removed or interfered with, the fire is extinguished. Fire fighting foam does not interfere in the chemical reaction. Foam works in the following ways:-

• The foam blankets the fuel surface thus resulting in smothering of fire.
• The foam blanket separates the flames from the fuel surface.
• The foam cools the fuel and any adjacent surfaces.
• The foam blanket suppresses the release of flammable vapors that can mix with air (oxygen).

Before moving further, please understand that there are two different basic flammable or combustible fuel groups.

• Standard hydrocarbon fuels such as gasoline, diesel, kerosene, jet fuel, etc. These products do not mix with water or do not mix with water, i.e. these products float on top of water and for the most part, they do not intermix.
• Polar solvent or Alcohol type fuels are fuels that mix readily with water or are miscible in water.

It is imperative that when you are preparing to fight a flammable liquid fire, you identify which fuel group the involved flammable liquid belongs. This is necessary, as some foam concentrates are not suitable for use on the Polar solvent/Alcohol type fuel spills or fires.

• AFFF Foam concentrate will apply to standard hydrocarbon fuels such as gasoline, diesel, kerosene, jet fuel, etc. immiscible with water.
• AR-AFFF (Alcohol Resistant) will be used to extinguishes fires of Polar solvent or Alcohol type fuels which mix readily with water.

Who Needs AFFF Fire Extinguishers

AFFF fire extinguishers are considered a good choice for general use and are suitable for use in most business premises. They are considered an ideal choice for premises where there are multiple fire risks. Few examples of such premises include:

• Hotels
• Garages
• Factories
• Offices
• Warehouses
• Hospitals

How To Use AFFF (Foam) Fire Extinguisher

The type of fire will determine how to use the extinguisher. However, all scenarios will have the same first step as follows:

First step in all scenarios will be to remove the safety pin to break the anti-tamper seal and stand at a safe distance.

For Flammable Liquid Fires:

• NEVER spray directly at the fire as this may cause it to spread to other areas
• In cases where the liquid is contained, use the extinguisher to point it right at the inside edge of the container
• In cases where the liquid is not contained, use a gentle sweeping motion either over the TOP of the fire or if there is an adjacent surface, then use this as the point of spray
• Following these steps will allow the foam to drop onto the fire so that it should settle over the burning liquid